The need sometimes arises for a system to provide a relatively precise quantity of solid, particle material along a length of solid strip material. For example, in the manufacture of welding electrode or wire, processes are well known in which solid particles, e.g., granular alloys or flux particles are deposited on a moving metallic strip, e.g., mild steel, after which the strip is tightly closed into a tubular configuration containing the particle material. This method for producing fabricated wire has been recognized to possess certain inherent advantages and is well known in the art.
With regard to welding wires generally, i.e., both fabricated and solid wires, current technology has resulted in a demand for products of greater uniformity. Of course, material deviations along a length of welding wire result in similar deviations in the resulting deposit. In many applications, such material variations are undesirable or even intolerable. Consequently, a need exists for an improved system for producing welding wire that is more uniform along its length, e.g., material content ratios are substantially constant from one section to another.
In the formation of solid welding wire, several manufacturing steps are generally involved with the result that material consistency is difficult to maintain both with respect to a single length of wire and lengths of wire produced from different billets. In the production of fabricated wires, several factors influence material consistency. The present invention relates to the recognition of such factors and the development of a system for controlling those factors to produce a relatively uniform fabricated welding wire.
Generally, the present invention is directed to a system for monitoring the flow of solid strip into a junction (at which particle material is to be received) and depositing a controlled amount of particle material on the strip to attain the desired material ratio relationship. Controlling the flow of the particle material accordingly involves apparatus for measuring flows of strip and particles, then precisely controlling the relationship between such flows. In accordance with the system, as disclosed herein, the section of the strip is monitored along with its speed of movement to develop the flow rate. Such data, along with information on the desired ratio, is processed to provide data indicative of the desired quantity of particle material. Flow of the particle material is then accordingly controlled and that flow is monitored to attain stability and improved accuracy by feedback techniques.